[PATCH 4/6] platform/apple: Add new Apple Mac SMC driver

[Hector Martin]

On 09/09/2022 16.50, Lee Jones wrote:
>> What's the point of just having effectively an array of mfd_cell and
>> wrappers to call into the mfd core in the drivers/mfd/ tree and the
>> rest of the driver elsewhere?
> 
> They should be separate drivers, with MFD registering the Platform.

Why? What purpose does this serve? I'm still confused. There's one
parent device, which provides services to the child devices. There isn't
one parent device which wraps a platform service which is used by
children. This makes no sense. The platform device is the root, if it
exposes MFD services, then it has to be in that direction, not the other
way around.

Look at how this patch series is architected. There is smc_core.c, which
implements SMC helpers and wrappers on top of a generic backend, and
registers with the MFD subsystem. And then there is smc_rtkit.c which is
the actual platform implementation on top of the RTKit framework, and is
the actual platform device entry point.

A priori, the only thing that makes sense to me right now would be to
move smc_core.c into drivers/mfd, and leave smc_rtkit.c in platform.
That way the mfd registration would be in drivers/mfd (as would be the
services offered to sub-drivers), but the actual backend implementation
would be in platform/ (and there would eventually be others, e.g. at
least two more for x86 systems). That does mean that the driver entry
point will be in platform/, with mfd/smc_core.c serving as effectively
library code to plumb in the mfd stuff into one of several possible
platform devices. Would that work for you?

- Hector